The present invention is directed to nano-composites, alternatively referred to as organo-clay. More particularly, the invention is directed to a cationic mediator comprised of a hydrophobic unit and a heterocyclic cationic unit used to prepare nano-composites and rubber compositions including the nano-composites.
Since the discovery of exfoliated nylon/clay nanocomposites by Usuki et al. (J. Mater. Res. 1993, 8, 1174), there have been extensive efforts directed to the preparation of various polymer-layered material composites. One common morphology for miscible polymer-layered material dispersions is known as intercalation and exfoliation, which improves polymeric properties such as mechanical, gas barrier/permeability, thermal, and heat distortion temperature. However, for polymers, particularly nonpolar polymers, well-exfoliated polymer-layered material nanocomposites are notoriously difficult to obtain.
Gas permeability is an important element of quality for many polymer products, for example, butyl rubber. Unsaturated bonds in butyl rubber, contributed by the presence of isoprene monomer units in the backbone, can be attacked by atmospheric ozone. These attacks may, over time, lead to oxidative degradation, which may subsequently lead to chain cleavage. As such, there exists a continuous interest in lowering gas permeability of polymer products by various techniques, among which is using well-exfoliated layered materials as an additive. However, other properties such as vulcanization plateau, hardness Shore A, cure capability, rubber damping properties, cure time, modulus, stress, moisture absorption, and strain etc. cannot be negatively impacted.
The present invention provides nano-composites and polymeric compositions derived from a cationic mediator, comprised of a hydrophobic unit and a heterocyclic cationic unit. Advantageously, the invention can employ compounds used as green solvents, e.g. 1-methylimidazol, as the reactant in preparing the cationic mediator, making both the process and product more environmentally friendly.